Nutritional and Health-Related Environmental Studies (NAHRES)

Zinc Nutrition during early life

Background

The World Health Organization (WHO) recommends exclusive breastfeeding for 6 months. Colostrum, which is rich in proteins and zinc, is gradually replaced by mature milk and, after the first month of lactation, human milk zinc concentration is low in comparison with cow's milk and decreases further as lactation progresses (Krebs 2000). As zinc concentration declines dramatically during early lactation concern has been raised about the potential risk of sub-optimal zinc intake in exclusively breastfed infants after the early months of lactation (Krebs 1999). The decrease in zinc concentration during early lactation has not been associated with maternal zinc intake and/or maternal zinc status. However, it should be noted that only very limited information is available, except for data from the US (Krebs et al 1995). For term infants, with normal birth weight, zinc requirements are generally assumed to be met by exclusive breastfeeding due to high bioavailability of zinc in human milk (Sandstrom et al 1983, Krebs et al 1996) and low excretion of endogenous zinc (Krebs et al 1996; Sian et al 2002). However, at 5 to 6 months of age, infants may become marginally zinc deficient (Walravens et al 1992), manifested by impaired growth.

Infants born with low birth weight (less than 2.5 kg) are of special concern due to rapid growth and therefore high requirements of zinc (Sur et al 2003). The prevalence of low birth weight infants is very high in many developing countries, for example in Bangladesh and Pakistan, and most of these infants are SGA (Hambidge and Krebs 2003).

The overall aim of this Coordinated Research Project (CRP) is to provide longitudinal data on human milk intake and the introduction of other fluids in different settings during the first year of life. In countries with high prevalence of SGA infants, SGA infants and infants appropriate for gestational age (AGA) will be studied in parallel. Well-established stable isotope technique "dose-to-the-mother deuterium turnover technique" as described by Coward et al (1982), Orr-Ewing et al (1986) and Haisma et al (2003) will be used to collect data on human milk intake and the introduction of other fluids. Longitudinal data on zinc concentration in human milk and infant growth rate will be collected in parallel. Newly developed stable isotope technique will be used to evaluate exchangeable pool sizes of zinc (as indicators of zinc status) in SGA and AGA infants in one or two settings (Krebs et al 2003).

The outcome of the CRP will contribute to a better understanding of zinc nutrition during early life. The results will be of particular relevance to countries where the prevalence of SGA infants is high and where there is an urgent need to develop effective nutrition interventions. In addition, the results will provide information on infant feeding patterns in different countries and will hopefully be used in the promotion of breast-feeding and the appropriate introduction of complementary foods.

Zinc in human milk will be analysed by sensitive and accurate analytical techniques. Neutron activation analysis (NAA), inductively coupled plasma mass spectrometry (ICP-MS) and atomic absorption spectrometry (AAS) will be used depending on availability in Member States. Deuterium enrichment of urine and/or saliva samples will be analysed by Fourier Transformed Infrared Spectrometer (FTIR) or by isotope ratio mass spectrometry. Zinc stable isotope ratios will be measured by ICP-MS or by thermal ionisation mass spectrometry (TIMS).


Objective
Overall objective

To contribute to a better understanding of zinc nutrition during the first year of life.

Specific objective
  • To evaluate human milk intake and the introduction of other fluids during the first year of life. In countries with high prevalence of small for gestational age (SGA) infants, SGA infants and infants appropriate for gestational age (AGA) will be studied in parallel
  • To evaluate changes in human milk zinc concentration (and zinc intake from human milk) during the first year of life.
  • To evaluate zinc status during early life, based on stable isotope techniques, in sub-groups of SGA and AGA infants.

Expected research outputs
  • Longitudinal data on human milk intake, zinc concentration in human milk, zinc intake from human milk, introduction of other fluids and growth rate during the first year of life.
  • New data on zinc status, based on stable isotope technique, in low birth weight infants (small for gestational age) and in infants appropriate for gestational age.

Proposal submission forms

Research institutions in Member States interested in participating in this CRP are invited to submit proposals directly to the Research Contracts Administration Section (NACA) of the International Atomic Energy Agency : Official.Mail@iaea.org or to Ms. Lena Davidsson: L.Davidsson@iaea.org.

The forms can be downloaded from http://www-crp.iaea.org/html/forms.html. For more information about research contracts and research agreements, please visit our web-site: http://www-crp.iaea.org/html/faqs.html.


Deadline for submission of proposals

Proposals must be received by the contract administration section or Ms. Lena Davidsson no later than August 1, 2005 . Transmission via E-mail is acceptable if all required signatures are scanned.

For additional information, please contact

Lena Davidsson
Section Head
Nutritional and Health Related Environmental Studies Section Division of Human Health
International Atomic Energy Agency (IAEA)
Wagramer Strasse 5 A-1400 Vienna Austria

Phone: + 43 1 2600 21657 or 21674
Fax: + 43 1 26007


Selected References
  1. Coward W, Cole T, Sawyer M, Prentice A. Breast milk intake measurement in mixed-fed infants by administration of deuterium oxide to their mothers. Hum Nutr Clin Nutr 1982; 36:141-8.
  2. Haisma H, Coward WA, Albernaz E, Vesser GH, Wells JC, Wright A, Victora CG. Breast milk and energy intake in exclusively, predominantly, and partially breast-fed infants. Eur J Clin Nutr 2003; 57(12):1633-42.
  3. Hambidge KM, Krebs NF. Zinc, low birth weight, and breastfeeding. Pediatrics 2003; 112:1419-20.
  4. Jones G, Steketee RW, Black RE, Bhutta ZA, Morris SS. How many child deaths can we prevent this year? Lancet 2003;362:65-71.
  5. Krebs NF. Zinc transfer to the breastfed infant. J Mammary Gland Biol Neoplasia 1999; 4:259-68.
  6. Krebs NF. Dietary zinc and iron sources, physical growth and cognitive development of breastfed infants. J Nutr 2000; 130(suppl):358S-60S.
  7. Krebs NF, Reidinger CJ, Hartley S, Robertson AD, Hambidge KM. Zinc supplementation during lactation: effects on maternal status and milk zinc concentrations. Am J Clin Nutr 1995;61:1030-6.
  8. Krebs NF, Reidinger CJ, Miller LV, Hambidge KM. Zinc homeostasis in breast-fed infants. Pediatr Res 1996;39:661-5.
  9. Krebs NF, Barlett A, Wescott JE, Rodden D, Wisner M, Lei S, Hambidge KM. Exchangeable zinc pool size is smaller at birth in small gestational age infants. Pediatr Res 2003; 53:394A.
  10. Orr-Ewing AK, Heywood PF, Coward WA. Longitudinal measurements of breast milk output by a 2H2O tracer technique in Rural Papua New Guinean women. Hum Nutr 1986; 40:457-67.
  11. Sandstrom B, Cederblad A, Lonnerdal B. Zinc absorption from human milk, cow's milk and infant formulas. Arch Pediatr Adolesc Med 1983; 137(8):726-9.
  12. Sanstead HH. Zinc deficiency. AJDC 1991;145:853-9.
  13. Sian L, Krebs NF, Westcott JW, et al. Zinc homeostasis during lactation in a population with low zinc intake. AJCN 2002;75:99-103.
  14. Sur D, Gupta DN, Mondal SK, et al. Impact of zinc supplementation on diarrheal morbidity and growth pattern of low birth weight infants in Kolkata, India: a randomized, double-blind, placebo-controlled, community-based study. Pediatrics 2003;112:1327-32.
  15. Walravens PA, Chakar A, Mokni R, Denise J, Lemonnier D. Zinc supplements in breastfed infants. Lancet 1992;340:683-5.
  16. World Health Organization. Zinc. In: Trace elements inhuman nutrition and health. Geneva: WHO; 1996.
  17. World Health Organization and UNICEF. Global strategy for infant and young child feeding. WHO, Geneva 2003